python - 图像的RGB矩阵 [英] python - RGB matrix of an image

问题描述

将图像作为输入，如何获得与之对应的rgb矩阵？
我检查了numpy.asarray函数。这给了我rgb矩阵或其他矩阵吗？

Taking an image as input, how can I get the rgb matrix corresponding to it? I checked out the numpy.asarray function. Does that give me the rgb matrix or some other matrix?

推荐答案

最简单的答案是在PIL周围使用NumPy和SciPy包装器。有一个很棒的教程，但基本的想法是：

The simplest answer is to use the NumPy and SciPy wrappers around PIL. There's a great tutorial, but the basic idea is:

from scipy import misc
arr = misc.imread('lena.png') # 640x480x3 array
arr[20, 30] # 3-vector for a pixel
arr[20, 30, 1] # green value for a pixel

对于640x480 RGB图像，这将为您提供640x480x3的 uint8 数组。

For a 640x480 RGB image, this will give you a 640x480x3 array of uint8.

或者你可以用PIL打开文件（或者更确切地说，Pillow;如果你还在使用PIL，这可能不起作用，或者可能非常慢）并直接传递给NumPy：

Or you can just open the file with PIL (or, rather, Pillow; if you're still using PIL, this may not work, or may be very slow) and pass it straight to NumPy:

import numpy as np
from PIL import Image
img = Image.open('lena.png')
arr = np.array(img) # 640x480x4 array
arr[20, 30] # 4-vector, just like above

这将为您提供类型为 uint8 的640x480x4数组（第4个为alpha; PIL始终将PNG文件作为RGBA加载，即使它们有不透明;如果您不确定，请参阅 img.getbands（）。

This will give you a 640x480x4 array of type uint8 (the 4th is alpha; PIL always loads PNG files as RGBA, even if they have no transparency; see img.getbands() if you're every unsure).

如果您不想使用NumPy，PIL自己的 PixelArray 类型是一个更有限的数组：

If you don't want to use NumPy at all, PIL's own PixelArray type is a more limited array:

arr = img.load()
arr[20, 30] # tuple of 4 ints

这给你一个640x480 PixelAccess RGBA 4元组数组。

This gives you a 640x480 PixelAccess array of RGBA 4-tuples.

或者你可以打电话给 getpixel 图片上：

Or you can just call getpixel on the image:

img.getpixel(20, 30) # tuple of 4 ints

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